With an active faith and conservative values, Fillon has promised to preserve traditional family values and to uphold France’s Catholic roots, and holds traditional views about marriage and abortion, though he has said he does not plan to overturn the 1975 law that legalized abortion.

“I will put the family at the heart of all public politics,” Fillon promised in a recent rally.

The family was “certainly not a place for dangerous social experimentation”, he said, referring to recently adapted adoption rights for same-sex couples.

Once one of the most Catholic countries in Europe, France has seen a steady decline in churchgoers over the years, with only 15 percent of the country’s 41.6 million Catholics who are considered regular or even occasional churchgoers today.

But there are still pockets in France where the social values of Catholicism have remained strong despite waning church numbers – explaining, at least in part, the success of Fillon.

“Zombie Catholics share certain symptoms: Not only do they hail from regions where resistance was greatest to the French Revolution, but they also have taken advantage of the benefits that flowed from the seismic event,” Zaretsky wrote.

“Highly educated and meritocratic, they also privilege a traditional ordering of professional and domestic duties between husbands and wives; strong attachment to social, community, and family activities; and a general wariness over the role of the state in private and community affairs, including ‘free schools’ (Catholic private schools).”

Fillon shares most of these characteristics, and was able to harness his appeal to the zombie Catholics for political gain.

Robert Zaretsky writes in Foreign Policy Magazine that Fillon has “never made any secret of his beliefs.” He hails from a deeply Catholic part of France, and goes on retreat every year.

Fillon recalls his Catholic upbringing fondly in his campaign book Faire (“To Make”), and explains how the Catholic worldview has shaped who he is as a person: “I was raised in this tradition, and I have kept this faith.”

Whether his popularity and appeal wlil hold long enough to win him the office remains to be seen. He will run against Marine Le Pen, the leader of the far-right National Front, and the Socialist nominee, which will be chosen in January. Incumbent president FranĂ§ois Hollande of the Socialist Party declined to run for another term.

The first round of the 2017 French presidential election will be held on April 23, 2017. Should no candidate win an outright majority, a second vote between the top two candidates will be held on May 7.